Check to be sure there is a good ground between the engine and the frame and/or the battery negative terminal. Also check for a ground wire between the generator housing and the regulator base- - - -install one if it's not there now. If there's a slightly high resistance anywhere between the generator and the battery, the charging current will try to go through the idiot light and cause it to glow. Check for clean, tight connections at the back of the ammeter, and the end of the wire from the ammeter where it attaches to the battery cable at the starter.
Jerry
